Method and apparatus for stretching and securing flexible sheets to a stiff support



I. v. VILLAGRASA 3,516,145 METHOD AND APPARATUS FOR STRETCHING AND SECURING June 23, 1970 FLEXIBLE SHEETS TO A STIFF SUPPORT 2 Sheets-Sheet 1 Filed May 12, 1967 a 6 7 I Y 4,

June 3' 1970 r 1. v. WLLAGRASA 3,515,145

METHOD AND APPARATUS FOR STRETCHING AND SECURING FLEXIBLE SHEETS TO A STIFF SUPPORT Filad. May 12, 1967 2 Sheets-Sheet 2 United States Patent Int. C1. 1323;) 11700; B21d 39/00 US. Cl. 29-24357 4 Claims ABSTRACT OF THE DISCLOSURE Apparatus for stretching and securing a flexible sheet to a stiff backing sheet by using narrow reinforcing strips inserted around the perimetrical margins thereof, the margins of the flexible sheet being folded around the reinforcing strips while they are bent into gripping engagement with the stiff material, and a method of performing these operations.

This invention relates to a mechanical process for spreading and fastening sheets onto stiffening supports, and also to a machine for the performance of this process.

In the conventional method where a sheet is glued to a surface such as cardboard or any other support, it frequently happens that the sheet, after it is dried, has wrinkles or lumps on its surface that detract from the appearance of the work.

On the other hand, this method of joining sheets, which are generally imprinted with some kind of information, to somewhat stiff supports, such as cardboard or sheets of "wood or metal, are presently widely used in many applications, as for example in posters, wall calendars, phonograph record jackets etc.

It is a principal object of this invention to provide a process that avoids the lumps or wrinkles mentioned above, but which at the same time does not produce any change in the gloss usually found on this type of printwork, or alter or attenuate its colors.

The present invention relates to the process for joining the perimeter of a flexible sheet of material such as paper to the perimeter of a support having a stiffness, such as cardboard, by means of narrow strips of very thin, light and foldable material which are inserted between the margins of the sheet and the edges of the support, the said margins are folded on the strips and the said margins and strips are bent and pressed onto the support.

The mechanical procedure of the present invention is characterized essentially in that, successively, the margins of the sheet to be mounted, folded substantially at aright dihedral angle, the respective edges of a stiff support placed on said sheet and being of smaller dimensions than the latter, and individual narrow and thin strips of malleable material having a length somewhat shorter than that of the respective edge of the stiff support, which are folded on their longitudinal axis at a dihedral angle of approximately 80 degrees and inserted between the said margins and edges so that one of the leaves of said strips folded at a dihedral angle is supported on the reverse of the sheet to be mounted and the other leaf is overlapped by the respective margin of the said sheet, which is folded at a dihedral angle, are introduced into a small cavity formed by an assembling table, a pressing member and a folding member similar to a dull-edged knife; the portion of said sheet margin overlapping said other leaf of the inserted strip is folded by means of the folding member around the free edge of this leaf toward 3,516,145 Patented June 23, 1970 ice the interior of the vertex of the dihedral angle formed by the said strip, and the assembly formed by said strip and the folded margin of the sheet is bent by means of the pressing member against the rigid support.

The machine invented for the practice of this process, which also forms part of the invention, comprises a bench on which there is disposed an electric motor with a pedal operated coupling device, and it is characterized essentially in that the said bench supports a horizontal assem bly table afiixed to it, a pressing member which has a turning movement of approximately degrees with return to its initial position, and a folding member similar to a dull-edged knife disposed on the said pressing member" and capable of performing a transverse translatory movement with respect to the latter, the said translatory movement being controlled by means of sinuous guides which can turn about a shaft affixed to the bench, and inside of which slide rods affixed to the bending member.

In the annexed, non-limitative drawings there is shown an embodiment of the present invention.

FIG. 1 is a lateral perspective view of the apparatus.

FIG. 2 is a perspective view of the back part of the apparatus.

FIG. 3 shows in elevation a detail of the clutch system.

FIG. 4 represents detail IV of FIG. 3 on a larger scale.

FIGS. 5 and 6 show detail V of FIG. 1 on a larger scale, at different phases of the procedure.

FIGS. 7 to 11 show sectional views of the folding and pressing members at different times of the procedure.

In FIGS. 1 and 2., the machine according to the invention comprises a frame 1 which serves as support to an electric motor 2, to an assembly table 3 and a pressing member 4 on which there is disposed a folding member 5 which is guided by means of guides 6 operated by connecting rods 7 joined by shaft 8 to pedal 9 which also operates connecting rod 10.

FIG. 3 shows the clutch device in the engaged position, which, in addition to a connecting rod 13', comprises a hand wheel 11, a wheel 12 and a flywheel 13, which are affixed to a shaft 14 which can revolve in bearings 15 affixed to the bench of the machine. A pulley 16 rotates freely on shaft 14 and is driven by motor 2 through a belt transmission system 17. As it can be seen in FIG. 4, wheel 12 has a bore 12' in which there is provided a compression spring 18 which acts on a pin 19 having a fixed collar 19'. The said pin 19 is the coupling between wheel 12 and pulley 16 when it plunges into one of the holes 20 provided in the said pulley 16. When wedge 21 is raised by connecting rod 10 when pedal 9 is released, it forces pin 19 to shift leftward by its action on collar 19, thus disengaging the clutch system.

As it can be seen from FIGS. 5 and 6, the folding member 5 has rods or lugs 22 affixed to it, which slide inside of guides 6.

In FIGS. 7 to 11 there is shown the placement of the sheet 23 which is to be mounted, the stiff backing 24 and the strip of malleable material 25 in the cavity formed by the assembly table 3, the pressing member 4 and the folding member 5. It will also be observed that the said folding member 5 is provided with bolts 26 affixed to it, which can slide along straight guiding slots 27 created trans versely in the pressing member 4, and these bolts, in conjunction with compression coil springs 26 of adjustable pressure, establish an elastic connection between the two said members; it is also provided, in the vicinity of its bottom edge, with rods 28, which are also aflixed to it, and which lodge in recesses 29 provided in the pressing member 4.

When the operating pedal 9 of the clutch device is depressed, two things occur simultaneously:

(a) A slight turn is made by the sinuous guides 6, as

3 it can be seen in FIGS. and 6, which obliges the folding member 5 to slide downward with respect to the pressing member 4.

(b) The clutch device is engaged and the motor 2 drives wheel 13 comprising the crank and connecting rod mechanism 1313 which in turn drives the pressing member 4 causing it to perform a 90 degree turn on a shaft afiixed to the bench and then returning it to the starting position whereupon the clutch device is automatically disengaged until the pedal 9 is depressed again to operate it.

The folding member 5, as stated, has bolts 26 affixed to it, which slide along straight guides 27 disposed trans versely in pressing member 4, and also it has close to its bottom edge some rods 28, also affixed to it, which lodge in individual recesses 29 provided in pressing member 4. When the folding member 5 descends, the said rods 28 come out of the said recesses 29 and oblige the bottom, dull edge of folding member 5 to move away from the pressing member 4; the rods 28 return into their respective recesses when the pressing member 4 returns to its starting position.

The above-mentioned sinuous guiding means 6 cause the folding member 5 to back off when the pressing member 4 begins its pressing action, by performing an upward translatory movement with respect to said pressing member.

The method of operation, according to the present invention, is as follows:

The printed sheet 23 (FIG. 7), appropriately trimmed and laid face down, is placed on the assembly table 3 of the machine, and support 24 is placed on top of it, the edge of said support being of lesser length than the sheet, so that a margin of the sheet 23 overlaps the support 24. Between the two there is inserted the strip of malleable material 25, which may have any reasonable Width and a thickness suitable to permit it to be doubled over, and which has previously been cut to a length that is still a few millimeters shorter than the edge of support 24, the said strip 25 being folded over approximately on its longitudinal axis to form a slightly acute dihedral angle.

Either of the leaves of the said strip 25 of malleable material is inserted between support 24 and sheet 23, and the other leaf is left so as to project above the thickness of support 24.

The portion of the printed sheet 23 that is not covered by support 24, and that has a normally horizontal position, is raised with the fingers, folded over and placed in contact with the raised leaf of malleable strip 25, so that the margin 23' of printed sheet 23 projects above the said leaf.

The assembly of printed sheet 23, strip of malleable material 25 and support 24, is then pushed to the bottom of the recess formed by the assembly table 3, the pressing member 4 and the folding member 5. The said recess is situated transversely to the machine and constitutes the zone of mechanical operation proper.

The pressing member 4 acts as a stop and keeps the margin 23 of printed sheet 23 together with the raised leaf of the strip of malleable material 25 and hold the two together against the edge of support 24, whereas the folding member 5 remains raised from the surface of table 3 at a height which is always less than that of margin 23' of the printed sheet 23 but greater than that of the raised leaf of the strip of malleable material 25, so that the folding member 5 forces the margin of printed sheet 23 to fold over on top of the raised leaf of the strip of malleable material 25 and to extend outward to such an extent that the margin 23' of printed sheet 23 projects outwardly in front of the folding member 5 (FIG. 7).

Once this position has been achieved, it is sufiicient to depress the operating pedal 9 of the clutch in order to start the machine in operation and complete the assembly of the side in question.

When pedal 9 is depressed, the sinuous guides 6 are drawn downward by means of the connecting rods 7 which connect them to pedal 9 and which cause the guides to turn about the shaft aifixed to the bench (FIGS. 5 and 6). Due to this slight turn the rods or lugs 22 affixed to the folding member 5 are moved downward, causing the latter to perform two movements, one descending translatory movement and the other a movement of separation (FIG. 8) of its bottom extremity, both with respect to the pressing member 4, thus acting on the margin 23' of the printed sheet 23 which projects in front of the folding member 5, and lowering it until it rests on the rigid support 24.

When pedal 9 is depressed, the clutch device (FIG. 4) is also engaged and the motor 2, which is constantly running, is connected to the crank and connecting rod mechanism 1313 which operates the pressing member 4. The latter turns forward on its fixed shaft (FIG. 9), carrying with it the folding member 5 which, though it must go along, performs several translatory movements with respect to the pressing member 4, which are guided by means of the sinuous guiding means 6.

As it has already been stated, the folding member is lowered until margin 23 has been placed on support 24, and then it pushes it all the way to the vertex of the dihedral angle formed by the strip of malleable material 25 and holds it there (so that the margin of the printed sheet has a zig-zag shape, as it can be seen in FIG. 9) until the precise moment in which the pressing member 4, in its turning movement, begins to press the raised leaf of the strip of malleable material 25 in the sense of joining the one leaf to the other; it is then that the folding member 5 begins withdrawing from the vertex (FIG. 10). The more the pressing member 4 joins together the leaves of the strip of malleable material 25, the more the folding member withdraws until it completely comes out of the interior of the said strip 25, remaining finally in a position with respect to the pressing member 4 which corresponds substantially to its initial position, and while this is happening, the pressing member goes on bending the leaf that was upraised and presses down harder the margin 23 of the printed sheet 23 that was turned under the said leaf and, upon reaching the end of the turn (FIG. 11), it compresses the leaf of the strip of malleable material 25 that was upraised against the support 24 and leaves it in a position that will be final, in such a manner that it firmly fastens the margin of the printed sheet 23 which remained between the strip of malleable material 25 and the support 24, thereby completing the assembly, and the pressing member 4 and the folding member 5, in their return movement, go back to their starting position; at this precise moment the clutch device is disengaged and the machine is ready to perform the assembly of another side of the whole.

I claim:

1. Apparatus for bending a generally L-shaped reinforcing strip and an overlapping marginal portion of flexible sheet material into gripping engagement with the marginal portion of a sheet of relatively stiff material, comprising assembly table means having a flat surface, elongated pressing means mounted for reciprocatory rotation about an axis parallel with said fiat surface said pressing means including an elongated flat surface portion normally disposed generally at right angles to said flat surface and movable into substantially face to face relationship therewith to bend said reinforcing strip into gripping engagement with the marginal portion of a sheet of material on said surface, folding means terminating in an elongated knife-edged marginal portion, means for mounting said folding means on said pressing means for reciprocatory translatory movement of the knife-edged portion in a sinuous path with respect to the pressing means generally parallel with the plane of the flat portion of the pressing means between a first position at one side of said flat portion, cam means mounted on the assembly table means for moving the knife-edged portion and reciprocatorily movable between a first position and a second position, for placing said knife-edged portion in its first and second positions respectively when the loding means is in its normal position, said knife-edged portion being returned to its first position by said cam means during movement of the pressing means to its face to face relationship with the flat surface of the assembly table means, motor means including clutch means for moving said pressing means, and pedal means for actuating said cam means and clutch means to simultaneously move the pressing means and folding means between said first position and the second position.

2. The apparatus as defined in claim 1, wherein the flat surface portion of the pressing means is normally disposed adjacent the fiat surface of the assembly table means for forming a cavity serving as a lodgement for the folded margin of a sheet of flexible material to be secured to a sheet of stiff material.

3. The apparatus as defined in claim 1, wherein said clutch means includes a driving wheel connected with the motor means and a coaxially mounted driven wheel, crank means connecting the driven wheel and the pressing means, normally engaged coupling means between the driving and driven wheels, and means actuated by the pedal means for normally urging disengagement of the coupling means and for releasing the coupling means for driving and pressing means.

4, The apparatus as defined in claim 1, wherein said pressing means includes a plate extending generally in the plane of the axis of rotation thereof, said plate being provided with axially spaced parallel radial slots, said folding means having members slidably received in said slots for supporting the folding means for limited sliding movement, spring means connected with said members for urging the folding means toward the pressing means, a rod secured to the folding means and spaced radially inwardly from said members for sliding engagement with a surface of said plate to position the knife-edged portion of the folding means during said sliding movement, said surface including a recessed portion to provide said sinuous path of movement of the knife-edged portion.

References Cited UNITED STATES PATENTS 542,071 7/1895 Westlake 29-24357 625,531 5/1899 Appleyard 29-24357 1,590,135 6/1926 Upham 2991.1 1,747,317 2/1930 Norris 29243.57 1,915,229 6/1933 Henry 29-243.57 2,330,662 9/1943 Balfe 29509 XR 2,781,818 2/1957 Beckman et a1. 2,959,205 11/1960 Day 29243.57

CHARLIE T. MOON, Primary Examiner US. Cl. X.R. 29-91.1, 509 

